Process for rust-proofing iron and steel.



D sTATns PATEET caries.

WILLIAM H. ALLEN, 015 DETROIT, MICHIGAN, ASSIGNOR To PARKER RUST PRoOE COMPANY OF AMERIOA, OE DETROIT, MICHIGAN, A CORPORATION OF MICHIGAN.

PROCESS FOR RUST-PROOFING IRON AND STEEL.

No Drawing. 9

To all whom it may concern:

Be it known that I, WILLIAM H. ALLEN, a citizen of the United States, and residing at Detroit, in the county of Wayne and State of Michigan, have invented a new and Improved Process for Rust-Proofing Iron and Steel, of which the following is a specification.

This invention relates to the rust-proofing of iron and steel through the .use of a solution of phosphoric acid or of acid ferrlc phosphates, with or without manganic OXid,

and it consists in removing the scale or other oxids from the surfaces to be rustproofed by means of a. strong, preferably hot, solution of phosphoric acid, and then immediately transferring the articles to the rust-proofing bath. The rust-proofing bath, preferably a saturated ferro-ferric I acid phosphate solution, may be prepared in any desirable manner} those described in the Richards Patent No. 1,069,903, dated August 12, 1913, or in the Allen Patent No. 1,167 966, dated January 11, 1916, being cited as examples.

This process of pickling cannot be. properly performed by sulfuric acid for the reason that the removal of all traces of its basic salts of iron is practically impossible, and as these basic sulfates are insoluble in the rust-proofing bath, blotches result which But when the articles are taken from the 4 hot strong phosphoric acid pickling bath and plunged immediately and before the solution can evaporate into the rust-proofing bath which is preferably composed of a sat- Specification of Letters Patent.

Application filed September 25, 1916. Serial No. 122,148.

Patented Mar. 20, 19119.

urated aqueous solution of acid ferrous and ferric phosphates, no such insoluble salts will be formed; the acid clinging to the articles will be taken up by the rust-proofing bath and there will be'formed on the articles being treated the desired black surface of basic phosphates of iron which are practically unaffected by the atmosphere.

The pickling bath is preferably from fifteen to twenty per cent. phosphoric acid and is kept at or near the boiling point. When iron or steel articles are placed therein the acid dissolves the iron and loosens the scale and other insoluble oxids.

1. The process of rust-proofing articles of iron and steel which consists in placing the same in a pickling solution of phosphoric acid to remove the scale and other insoluble oxids and then immediately submerging these. articles in a rust-proofing bath containing compounds of phosphorus before .the adherent pickling solution has time to .evaporate. I

2. The process of rust-proofing articles of iron and steel which consists in placing J them in a hot pickling solution of phos-- phoric acid to remove the scale and other insoluble Oxids, then taking the articles from this solution and before the pickling solu-.

tion hashad time to evaporate submerging the articles in an aqueous solution of acid ferrous and ferric ,phosphates until black basic phosphates of iron are formed on the surfaces of such articles.

3. The process of rust-proofing articles of iron and steel whichconsists in placing the same. in a pickling bath consisting of about five parts "of watei" and one part of phosphoric 'acid to remove the scale and other insoluble oxids and then immediately before the adherent moisture has ,time to evaporate, submerging these articles in a rust-proofing bath containing compounds of phosphorus. 4. The-process of rust-proofing them in a pickling sclutionof phosphoric acid, then taking the articles from thissolution and before the pickling solution has articlesof iron and steel which consists in placing I I 1,219,526 I had time to evaporate submerging-the articles in a bath containing an aqueous solu tion of a phosphate of iron.

5. The process of rust-proofing articlesof 5- iron and steel which consists in placing them in a pickling solutionof phosphoric acid, then takingthe' articles from this solution and before the pickling solution-has had time to evaporate submerging the articles in a bath containing a form of phosphorus 10 until basic phosphates of iron are formed on the surface of such article.

WILLIAM H. ALLEN. 

